add posthog for session analytics

Sentry for errors, PostHog for pass/fail analytics with device info.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: adeebshihadeh

.env

@@ -1 +1,3 @@
 VITE_SENTRY_DSN=https://[email protected]/4510604761825280
+VITE_PUBLIC_POSTHOG_KEY=phc_O4kXIsdyB2cm9Wne1pwJkj5jk9Ua51ABVPAhtSuYQ4V
+VITE_PUBLIC_POSTHOG_HOST=https://us.i.posthog.com

package-lock.json

@@ -16,6 +16,7 @@
     "@commaai/qdl": "git+https://github.com/commaai/qdl.js.git#21d7be79fa5178f253d32a0879bd8bdd4fa37e30",
     "@fontsource-variable/inter": "^5.2.5",
     "@fontsource-variable/jetbrains-mono": "^5.2.5",
+    "posthog-js": "^1.310.1",
     "react": "^18.3.1",
     "react-dom": "^18.3.1",
     "xz-decompress": "^0.2.2"

package.json

@@ -1,4 +1,5 @@
 import { useEffect, useRef, useState } from 'react'
+import posthog from 'posthog-js'
 import { addBreadcrumb, setTags, setTag, setContext, captureSessionSummary } from '../utils/telemetry'
 
 import { FlashManager, StepCode, ErrorCode, DeviceType } from '../utils/manager'
@@ -736,6 +737,20 @@ export default function Flash() {
   function sendSessionSummary(result) {
     if (reportSentRef.current) return
     reportSentRef.current = true
+
+    const errorName = Object.keys(ErrorCode).find(k => ErrorCode[k] === error) || 'NONE'
+    const stepName = Object.keys(StepCode).find(k => StepCode[k] === step) || 'UNKNOWN'
+
+    // PostHog event
+    posthog.capture('flash_session', {
+      result,
+      serial,
+      device_type: selectedDevice,
+      error_code: errorName,
+      step: stepName,
+    })
+
+    // Sentry (for errors with full context)
     const meta = {
       ...buildEnvMeta(),
       selectedDevice,

src/app/Flash.jsx

@@ -1,5 +1,6 @@
 import React from 'react'
 import ReactDOM from 'react-dom/client'
+import posthog from 'posthog-js'
 import { initSentry } from './utils/telemetry'
 
 import '@fontsource-variable/inter'
@@ -8,6 +9,18 @@ import '@fontsource-variable/jetbrains-mono'
 import './index.css'
 import App from './app'
 
+// Initialize PostHog
+if (import.meta.env.VITE_PUBLIC_POSTHOG_KEY) {
+  posthog.init(import.meta.env.VITE_PUBLIC_POSTHOG_KEY, {
+    api_host: import.meta.env.VITE_PUBLIC_POSTHOG_HOST,
+    capture_pageview: false,  // We'll track manually
+    persistence: 'memory',    // Don't persist across sessions
+  })
+}
+
+// Initialize Sentry (no-op if DSN unset)
+initSentry()
+
 // Explicitly load fonts before rendering to prevent FOUT
 async function loadFonts() {
   await Promise.all([
@@ -16,9 +29,6 @@ async function loadFonts() {
   ])
 }
 
-// Initialize telemetry (no-op if DSN unset)
-initSentry()
-
 loadFonts().then(() => {
   ReactDOM.createRoot(document.getElementById('root')).render(
     <React.StrictMode>